The Study On The Wear Resistance Of Diamond-Like Carbon Deposited On The Materials For Artificial Mechanical Valves

Two types of failures of artificial mechanical heart valves (AMHV) have been immersed in clinic, which included complications of biological issue such as thrombosis and infection, and mechanical failure involving the valve damage and fatigue abrasion etc. Surface modification has been applied for resolving the two issues. More efforts have been paied for improving the biocompatibility of mechanical valves, whereas less research have been done for enhanceing mechanical performance of AHMV by surface modification, especially the wear resistance, this dissertation worked on improving the wear resistance of mechanical valves by symthsied diamond-like carbon (DLC) films on two types of materials for artificial bileaflet valves.DLC films were synthesized on the Ti6A14V wafers which fixed inside the valve ring by filtered cathodic vacuum arc deposition (FCVAD) and plasma immersion ion implantation and deposition (PIIID), separately. The films were characterized by a wear test and X-ray photoelectron spectroscopy (XPS) to obtain their abrasive performance and status of chemical bonds. Besides, DLC films were prepared on Ti6A14V valve rings and leaflets made of low temperature isotropic carbon (LTIC), and the both films were detected by XPS, while the latter were investigated by the simulative wear test.The results showed that the DLC film with its content of C-C sp3bonds to about66.9%was coated on Ti6A14V wafers by FCVAD, and which presented good wear resistance in simulated body fluid (SBF). Besides, the DLC film on Ti6A14V wafers made by PIIID containing about59.4%of sp3bonds was generally intact after the wear test, and increasing the negative bias voltage can benefit to better abrasion resistance. Moreover, the DLC film deposited on the Ti6A14V ring with round pivots by FCVAD possessed a content of sp3bonds to about65.1%, compared with53.3%of the film on the ring with butterfly pivots. Furthermore, the DLC film containing about67.9%sp3bonds coated on LTIC leaflets by FCVAD exhibited good wear resistance after rubbing against the DLC film on Ti6Al4V wafers during the simulative fiction test.